Multilayer graphene sheets (MLGSs) are promising nano-reinforcements that can effectively enhance the mechanical properties of polymer matrices. Despite many studies on MLGSs-reinforced polymer ...nanocomposites, the effect of wrinkles formed in MLGSs on the reinforcement effect and the viscoelastic properties of polymer nanocomposites has remained largely unknown. In this study, building upon previously developed coarse-grained models of MLGSs and poly(methyl methacrylate) coupled with molecular dynamics simulations, we have systematically investigated nanocomposites with different numbers of graphene layers and various wrinkle configurations. We find that with decreasing degree of waviness and increasing numbers of layers, the elastic modulus of the nanocomposites increases. Interestingly, we observe a sudden stress drop during shear deformation of certain wrinkled MLGSs-reinforced nanocomposites. We further conduct small amplitude oscillatory shear simulations on these nanocomposites and find that the nanocomposites with these specific wrinkle configurations also show peculiarly large loss tangents, indicating an increasing capability of energy dissipation. These behaviors are attributed to the activation of the interlayer sliding among these wrinkled MLGSs, as their interlayer shear strengths are indeed lower than flat MLGSs measured by steered molecular dynamics technique. Our study demonstrates that the viscoelastic properties and deformation mechanisms of polymer nanocomposites can be tuned through MLGS wrinkle engineering.
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Polymeric micelles (PM) system, as an efficient drug carrier, has received growing scientific attention in recent years owing to its solubilization, selective targeting, P-glycoprotein inhibition and ...altered drug internalization route and subcellular localization properties. Seven PM formulations of anti-tumor drugs being evaluated in clinical trials are reviewed in this paper, in terms of formulation study, in vitro cytotoxicity, in vivo pharmacokinetics, anti-tumor efficacy and safety as well as clinical trials, to shed new light on the discovery of novel PM formulations. In these seven PM formulations, PM system was employed to overcome the issues of low water solubility, high toxicity and (or) multidrug resistance accompanied with the conventional formulation, which greatly hampered their clinical application. Those promising preclinical and clinical results combined with rapid advancement and intense multidisciplinary collaboration enable the extension of the PM system to traditional Chinese medicine, imaging agents, gene and combination agent deliveries as well as some other administration routes, which facilitate the clinical translation of the PM drug delivery system.
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Due to the inherent resistance of bacterial biofilms to antibiotics and their serious threat to global public health, novel therapeutic agents and strategies to tackle biofilms are urgently needed. ...To this end, we designed and synthesized a novel guanidinium‐functionalized pillar5arene (GP5) that exhibited high antibacterial potency against Gram‐negative E. coli (BH101) and Gram‐positive S. aureus (ATCC25904) strains. More importantly, GP5 effectively disrupted preformed E. coli biofilms by efficient penetration through biofilm barriers and subsequent destruction of biofilm‐enclosed bacteria. Furthermore, host–guest complexation between GP5 and cefazolin sodium, a conventional antibiotic that otherwise shows negligible activity against biofilms, exhibited much enhanced, synergistic disruption activity against E. coli biofilms, thus providing a novel supramolecular platform to effectively disrupt biofilms.
Guanidinium‐functionalized pillar5arene (GP5) exhibited antibacterial activity against both Gram‐negative E. coli and Gram‐positive S. aureus bacterial strains. More significantly, it showed strong biofilm‐disrupting activity against preformed E. coli biofilms. Host–guest complexation between GP5 and a conventional antibiotic, cefazolin sodium, provides a supramolecular strategy for synergistically enhanced disruption of bacterial biofilms (see picture).
Nanomaterials based on chitosan have emerged as promising carriers of therapeutic agents for drug delivery due to good biocompatibility, biodegradability, and low toxicity. Chitosan originated ...nanocarriers have been prepared by mini-emulsion, chemical or ionic gelation, coacervation/precipitation, and spray-drying methods. As alternatives to these traditional fabrication methods, self-assembled chitosan nanomaterials show significant advantages and have received growing scientific attention in recent years. Self-assembly is a spontaneous process by which organized structures with particular functions and properties could be obtained without additional complicated processing or modification steps. In this review, we focus on recent progress in the design, fabrication and physicochemical aspects of chitosan-based self-assembled nanomaterials. Their applications in drug delivery of different therapeutic agents are also discussed in details.
Andrographis paniculata (A. paniculata) is a medicinal plant traditionally used as anti-inflammation and anti-bacteria herb. Andrographolide, the major active component of A. paniculata, exhibits ...diverse pharmacological activities, including anti-inflammation, anti-cancer, anti-obesity, anti-diabetes, and other activities. In this article, we comprehensively review the therapeutic potential of A. paniculata and andrographolide focusing on the mechanisms of action and clinical application. We systemically discuss the structure-activity relationship of andrographolide and derivatives. Despite the various pharmacological activities and formula of A. paniculata and andrographolide, we propose further development of more structural derivatives of andrographolide with reduced toxicity and increased therapeutic efficacy is still needed for the clinical application of this ancient mighty herb and its major component.
Salvia miltiorrhiza Bunge (Danshen in Chinese) is a classical Huoxue Huayu (a traditional Chinese medical term means promoting blood circulation and removing blood stasis) herb with 1000 years of ...clinical application. It mainly contains two groups of ingredients: the hydrophilic phenolic acids and the lipophilic tanshinones. Both groups have demonstrated multiple bioactivities, such as antioxidative stress, antiplatelet aggregation, anti‐inflammation, among others. Recent data have demonstrated that its lipophilic compounds, especially the tanshinones, show potent anticancer activities both in vitro and in vivo. The anticancer effects of the hydrophilic phenolic acids have also been reported. Furthermore, tanshinones provide structural skeletons for chemical modifications, allowing for a series of derivatives of interests. This review provides a systematic summary of the anticancer profile and the underlying mechanisms of the bioactive compounds isolated from Danshen with special emphasis on tanshinones, aiming to bring new insights for further research and development of this ancient herb.
Plant DNA barcoding: from gene to genome Li, Xiwen; Yang, Yang; Henry, Robert J. ...
Biological reviews of the Cambridge Philosophical Society,
February 2015, Volume:
90, Issue:
1
Journal Article
Peer reviewed
ABSTRACT
DNA barcoding is currently a widely used and effective tool that enables rapid and accurate identification of plant species; however, none of the available loci work across all species. ...Because single‐locus DNA barcodes lack adequate variations in closely related taxa, recent barcoding studies have placed high emphasis on the use of whole‐chloroplast genome sequences which are now more readily available as a consequence of improving sequencing technologies. While chloroplast genome sequencing can already deliver a reliable barcode for accurate plant identification it is not yet resource‐effective and does not yet offer the speed of analysis provided by single‐locus barcodes to unspecialized laboratory facilities. Here, we review the development of candidate barcodes and discuss the feasibility of using the chloroplast genome as a super‐barcode. We advocate a new approach for DNA barcoding that, for selected groups of taxa, combines the best use of single‐locus barcodes and super‐barcodes for efficient plant identification. Specific barcodes might enhance our ability to distinguish closely related plants at the species and population levels.
Triptolide and celastrol are predominantly active natural products isolated from the medicinal plant
Hook F. These compounds exhibit similar pharmacological activities, including anti-cancer, ...anti-inflammation, anti-obesity, and anti-diabetic activities. Triptolide and celastrol also provide neuroprotection and prevent cardiovascular and metabolic diseases. However, toxicity restricts the further development of triptolide and celastrol. In this review, we comprehensively review therapeutic targets and mechanisms of action, and translational study of triptolide and celastrol. We systemically discuss the structure-activity-relationship of triptolide, celastrol, and their derivatives. Furthermore, we propose the use of structural derivatives, targeted therapy, and combination treatment as possible solutions to reduce toxicity and increase therapeutic window of these potent natural products from
Hook F.
Abstract MicroRNAs (miRNAs) play critical roles in modulating the oncogenic driver pathways involved in the acquisition of resistance to cancer treatments. MiR-542-3p serves as a potent tumor ...suppressor molecule by targeting tumor suppressor p53 and apoptosis inhibitor survivin. A hyaluronic acid (HA)-decorated polyethylenimine-poly( d , l -lactide-co-glycolide) (PEI-PLGA) nanoparticle system was developed in this study for targeted co-delivery of doxorubicin (DOX) and miR-542-3p for triple negative breast cancer (TNBC) therapy. This system showed an average size at 131.7 nm and high drug encapsulation efficiency, and prevented miR-542-3p degradation in the serum. HA/PEI-PLGA nanoparticles increased both drug uptake and cytotoxicity in MDA-MB-231 cells compared to MCF-7 cells, which express lower CD44 levels. Intracellular restoration of miR-542-3p further promoted TNBC cell apoptosis via activating p53 and inhibiting survivin expression. These results indicate that HA/PEI-PLGA nanoparticles have the potential to co-deliver chemotherapeutic agents and tumor suppressive miRNAs in combinatorial TNBC therapy.
Datura stramonium is a widely used poisonous plant with great medicinal and economic value. Its chloroplast (cp) genome is 155,871 bp in length with a typical quadripartite structure of the large ...(LSC, 86,302 bp) and small (SSC, 18,367 bp) single-copy regions, separated by a pair of inverted repeats (IRs, 25,601 bp). The genome contains 113 unique genes, including 80 protein-coding genes, 29 tRNAs and four rRNAs. A total of 11 forward, 9 palindromic and 13 tandem repeats were detected in the D. stramonium cp genome. Most simple sequence repeats (SSR) are AT-rich and are less abundant in coding regions than in non-coding regions. Both SSRs and GC content were unevenly distributed in the entire cp genome. All preferred synonymous codons were found to use A/T ending codons. The difference in GC contents of entire genomes and of the three-codon positions suggests that the D. stramonium cp genome might possess different genomic organization, in part due to different mutational pressures. The five most divergent coding regions and four non-coding regions (trnH-psbA, rps4-trnS, ndhD-ccsA, and ndhI-ndhG) were identified using whole plastome alignment, which can be used to develop molecular markers for phylogenetics and barcoding studies within the Solanaceae. Phylogenetic analysis based on 68 protein-coding genes supported Datura as a sister to Solanum. This study provides valuable information for phylogenetic and cp genetic engineering studies of this poisonous and medicinal plant.
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